Abstract
This study investigates the potential of ultrasound treatment to enhance the viability and efficacy of Lacticaseibacillus paracasei (L. paracasei) in bread production. Given the increasing consumer demand for probiotic-enriched foods, bread represents a promising vehicle for these beneficial microorganisms. Nevertheless, the high temperatures involved in traditional baking processes significantly reduce probiotic cell viability, limiting the functional effectiveness of probiotic-enriched breads. High-intensity ultrasound (HIU) has emerged as a potential strategy to enhance probiotic viability and stimulate microbial metabolic pathways, thus potentially improving probiotic performance throughout bread fermentation and baking processes. Results indicated that certain controlled ultrasound treatments promoted L. paracasei growth and metabolic activity. Specifically, treatments at lower power did not affect the immediate viability of the cells, while higher power caused a significant reduction. However, after recovery incubation, certain treated groups exhibited improved growth, indicating that specific ultrasound parameters could foster cell growth and propagation. During bread proofing, ultrasound-treated probiotics showed a slight but significant increase in cell growth. In the baking phase, while the overall viability of L. paracasei decreased, ultrasound-treated cells demonstrated enhanced heat resistance. Furthermore, the addition of L. paracasei in the dough positively impacted dough height, stability, and gas retention. Bread with added L. paracasei, both treated and untreated, revealed improvements in texture, specific volume, moisture content, and pH. In conclusion, carefully optimised ultrasound pre-treatment demonstrates substantial potential for improving probiotic-related viability and processing performance within bread systems. Further research is needed to optimise ultrasound parameters and to elucidate the underlying mechanisms responsible for the protective effects observed during bread processing.